Stack Abuse: How to Upload Files with Python's requests Library

Introduction

Python is supported by many libraries which simplify data transfer over HTTP. The requests library is one of the most popular Python packages as it's heavily used in web scraping. It's also popular for interacting with servers! The library makes it easy to upload data in a popular format like JSON, but also makes it easy to upload files as well.

In this tutorial, we will take a look at how to upload files using Python's requests library. The article will start by covering the requests library and the post() function signature. Next, we will cover how to upload a single file using the requests package. Last but not least, we upload multiple files in one request.

Uploading a Single File with Python's Requests Library

This tutorial covers how to send the files, we're not concerned about how they're created. To follow along, create three files called my_file.txt, my_file_2.txt and my_file_3.txt.

The first thing we need to do is install our the request library in our workspace. While not necessary, it's recommended that you install libraries in a virtual environment:

$ python3 -m venv .

Activate the virtual environment so that we would no longer impact the global Python installation:

$ . bin/activate

Now let's install the requests library with pip:

$ pip install requests

Create a new file called single_uploader.py which will store our code. In that file, let's begin by importing the requests library:

import requests

Now we're set up to upload a file! When uploading a file, we need to open the file and stream the content. After all, we can't upload a file we don't have access to. We'll do this with the open() function.

The open() function accepts two parameters: the path of the file and the mode. The path of the file can be an absolute path or a relative path to where the script is being run. If you're uploading a file in the same directory, you can just use the file's name.

The second argument, mode, will take the "read binary" value which is represented by rb. This argument tells the computer that we want to open the file in the read mode, and we wish to consume the data of the file in a binary format:

test_file = open("my_file.txt", "rb")

Note: it's important to read the file in binary mode. The requests library typically determines the Content-Length header, which is a value in bytes. If the file is not read in bytes mode, the library may get an incorrect value for Content-Length, which would cause errors during file submission.

For this tutorial, we'll make requests to the free httpbin service. This API allows developers to test their HTTP requests. Let's create a variable that stores the URL we'll post our files to:

test_url = "http://httpbin.org/post"

We now have everything to make the request. We'll use the post() method of the requests library to upload the file. We need two arguments to make this work: the URL of the server and files property. We'll also save the response in a variable, write the following code:

test_response = requests.post(test_url, files = {"form_field_name": test_file})

The files property takes a dictionary. The key is the name of the form field that accepts the file. The value is the bytes of the opened file you want to upload.

Normally to check if your post() method was successful we check the HTTP status code of the response. We can use the ok property of the response object, test_url. If it's true, we'll print out the response from the HTTP server, in this case, it will echo the request:

if test_response.ok:
    print("Upload completed successfully!")
    print(test_response.text)
else:
    print("Something went wrong!")

Let's try it out! In the terminal, execute your script with the python command:

python single_uploader.py

Your output would be similar to this:

Upload completed successfully!
{
  "args": {}, 
  "data": "", 
  "files": {
    "form_field_name": "This is my file\nI like my file\n"
  }, 
  "form": {}, 
  "headers": {
    "Accept": "*/*", 
    "Accept-Encoding": "gzip, deflate", 
    "Content-Length": "189", 
    "Content-Type": "multipart/form-data; boundary=53bb41eb09d784cedc62d521121269f8", 
    "Host": "httpbin.org", 
    "User-Agent": "python-requests/2.25.0", 
    "X-Amzn-Trace-Id": "Root=1-5fc3c190-5dea2c7633a02bcf5e654c2b"
  }, 
  "json": null, 
  "origin": "102.5.105.200", 
  "url": "http://httpbin.org/post"
}

As a sanity check, you can verify the form_field_name value matches what's in your file.

Uploading Multiple Files with Python's requests Library

Uploading multiple files using requests is quite similar to a single file, with the major difference being our use of lists. Create a new file called multi_uploader.py and the following setup code:

import requests

test_url = "http://httpbin.org/post"

Now create a variable called test_files that's a dictionary with multiple names and files:

test_files = {
    "test_file_1": open("my_file.txt", "rb"),
    "test_file_2": open("my_file_2.txt", "rb"),
    "test_file_3": open("my_file_3.txt", "rb")
}

Like before, the keys are the names of the form fields and the values are the files in bytes.

We can also create our files variables as a list of tuples. Each tuple contains the name of the form field accepting the file, followed by the file's contents in bytes:

test_files = [("test_file_1", open("my_file.txt", "rb")),
              ("test_file_2", open("my_file_2.txt", "rb")),
              ("test_file_3", open("my_file_3.txt", "rb"))]

Either works so choose whichever one you prefer!

Once the list of files is ready, you can send the request and check its response like before:

test_response = requests.post(test_url, files = test_files)

if test_response.ok:
    print("Upload completed successfully!")
    print(test_response.text)
else:
    print("Something went wrong!")

Execute this script with the python command:

$ python multi_uploader.py

You'll see this output:

Upload completed successfully!
{
  "args": {}, 
  "data": "", 
  "files": {
    "test_file_1": "This is my file\nI like my file\n", 
    "test_file_2": "All your base are belong to us\n", 
    "test_file_3": "It's-a me, Mario!\n"
  }, 
  "form": {}, 
  "headers": {
    "Accept": "*/*", 
    "Accept-Encoding": "gzip, deflate", 
    "Content-Length": "470", 
    "Content-Type": "multipart/form-data; boundary=4111c551fb8c61fd14af07bd5df5bb76", 
    "Host": "httpbin.org", 
    "User-Agent": "python-requests/2.25.0", 
    "X-Amzn-Trace-Id": "Root=1-5fc3c744-30404a8b186cf91c7d239034"
  }, 
  "json": null, 
  "origin": "102.5.105.200", 
  "url": "http://httpbin.org/post"
}

Good job! You can upload single and multiple files with requests!

Conclusion

In this article, we learned how to upload files in Python using the requests library. Where it's a single file or multiple files, only a few tweaks are needed with the post() method. We also verified our response to ensure that our uploads were successful.

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